This invention relates to a bending machine for bending rod-shaped and/or bar-shaped workpieces and in particular pipes, employing a bending device that encompasses selectively deployable bending tools of which at least one is provided on one side and at least one on the opposite side of a tool platen, each of which tools includes at least one bending swage and at least one thrust member, which for switching between an operating and an idle position can be power driven back and forth in the transverse direction of the workpiece. The bending swages are positioned on a bending axis that extends in the transverse direction of the workpiece, with the operating position of at least one thrust member on one side of the tool platen permitting the concurrent idling of at least one thrust member on the other side of the tool platen while the workpiece on the active bending tool, when effectively impacted in the transverse direction of the workpiece, can be bent around the bending swage by means of at least one of the thrust members when in its operating position.
The invention relates in particular to a bending machine of this type that employs thrust members in the form of slide rails, whereby, as the workpiece is bent around the bending swage, it can be braced on the active bending tool in the transverse direction of the workpiece by at least one slide rail that has assumed its operating position in the transverse direction of the workpiece.
Bending machines of the type referred to above have been described in European Patent No. B-0 538 207. These prior-art designs incorporate multi-level bending tools that are positioned on opposite sides of a tool platen and encompass in each case several bending swages in an over-under arrangement in the direction of a bending axis as well as clamping jaws and slide rails that interact with the bending swages. These are conventional rotational bending tools whose clamping jaws and slide rails can be moved back and forth between their operating and their idle position by means of a hydraulic drive system. In the case of the prior-art design, the clamping jaws and slide rails on one side of the tool platen are activated and moved independently of the clamping jaws and slide rails on the opposite side of the tool platen, for which purpose the clamping jaws and slide rails on either side of the tool platen have their own individual hydraulic drive systems in the form of hydraulic piston-and-cylinder units.
A conceptually different bending machine is described in German Patent 33 02 888. That machine features a bending head for the joint processing of two pipes, which, for that purpose, is provided with two simultaneously operable rotational bending tools. By means of a single piston and cylinder unit the clamping jaws of the two rotational bending tools can be jointly moved into an operating or an idle position. Accordingly, the slide rails of these two earlier rotational bending tool designs are jointly driven back and forth in the transverse direction of the workpiece by a single piston and cylinder unit between an operating position next to the workpiece and an idle position retracted from the workpiece. In the longitudinal direction of the workpiece the slide rails of the two bending tools are moved along by the pipes in process as these are being bent. In other words, no feed drive is provided for moving the slide rails during the processing of the pipes. Once the two pipes in process have been bent, a common piston and cylinder unit retracts the slide rails jointly into their home position.
It is the objective of this invention to provide a bending machine which is structurally simplified from the first-mentioned prior art design while ensuring optimal functional reliability.